Stabilised 5m Liberty Like kite & 4m Flexifoil Blade

I see that it is nearly 3 years since the last article.  Although some development has been attempted, various responsibilities away from the water have precluded much action.  Hopefully, however, KitetiK will be able to sail to Moreton Island this summer.

The quest for a kite that is stable in traction mode continues.  I have a 20m Liberty, from Beyond-the-sea, purchased through my buddies at Amorkite in Brittany.  That has only been used a couple of times.  Although it's never going to produce high performance, it looks promising for at least getting moving single handed.  A set of rigging, essentially two tow points and a few barber hauler points, was tested with Michael on Monday evening in light breeze - after an excellent Matso's ginger beer.  We remained attached to the mooring. But the rigging plan looks to have potential.  This will allow trimming for different points of sail (different apparent wind angles) including shunting (the proa version of tacking) dynamically.  More on that when we actually leave the mooring.

Before getting the Liberty I'd attempted to make something similar.  The Liberty is stabilised by having the 2 tow points separated horizontally about 100° from the apparent wind angle - ie in line with the kite lines.  Even with all the real estate provided by KitetiK, this presents certain challenges.  My objective was to have something that would be similarly stable but without the need for the tow point separation.  This necessitates (so far....) 4 lines rather than just 2 - so that's a significant disadvantage.  But it means that the 4 lines can be connected at essentially one point with stabilisation coming from a short mast at that point.  The geometry is similar to what is documented here: .  This has 2 advantages.  Firstly, with the tow points to leeward, there is no heeling moment.  With the size of kites and wind conditions I'll be experiencing in the short term, this is not important.  But, longer term, I hope to have sufficient power for that to be relevant.  Secondly, with all lines connected to the vessel on a single vertical axis, no trimming is needed as the apparent wind angle changes - the kite flies to the position dicated by the lift:drag ratio of the system.  The kite would be manually steered through zenith when shunting. The stabilising line would need to be switched from the previously upper wingtip to the new one. 


A quite different idea for stabilising elevation may be possible if, as is planned, KitetiK gets a mast.  Not only will a mast facilitate launching, but a halyard from the upper wing tip can, it seems, stop the kite from dropping (ie reducing elevation).  This was tried with a somewhat poorly trimmed single skin kite - without much success.  It seems that the tension on the wing tip distorts it enough to stop it flying.  Today I tried a 4m Flexifoil Blade.  It's not really a fair test as the bridles require fairly wide separation when there are no lines attached.  And that separation provides some stability.  But, the video below demonstrates that the halyard does tighten but does not collapse the kite.  The objective would be to do something similar with a large paraglider with the risers at the mast base.  I may need to rebridle the blade in order to do a more useful test.  The kite flew in this configuration for 15 minutes with very little movement - in this video the breeze was a little light (6-8 knots) so it drifted around a little more than when it was closer to 10 knots.  The astonishing thing was that none of the (non-kite-interested) passers by at the park seemed the least impressed!


Usually the difficulty with kite tests is not enough wind or wind that is too shifty (as they are mostly performed on land).  Conditions were mostly benign today, around 8 to 10 knots.  Next tests will have to be in more wind.  And longer lines for the arc kite.